AttributeError的：「InstrumentedList」對象沒有屬性

Question

我有這些表的表：

class Thing(Base): 
    __tablename__ = 'thing' 
    id = Column(Integer, primary_key=True) 

class User(Base): 
    __tablename__ = 'user' 
    id = Column(Integer, primary_key=True) 

class Voteinfo(Base): 
    __tablename__ = 'voteinfo' 
    thing_id = Column(Integer, ForeignKey('thing.id'), primary_key=True) 
    thing = relationship('Thing', backref='voteinfo') 
    upvotes = Column(Integer) 
    downvotes = Column(Integer) 

    def __init__(self, thing) 
     self.thing = thing 

class VoteThing(Base): 
    __tablename__ = 'votething' 
    id = Column(Integer, primary_key=True) 
    voter_id = Column(Integer, ForeignKey('voter.id')) 
    voter = relationship('Voter', backref='votescast') 
    thing_id = Column(Integer, ForeignKey('thing.id')) 
    thing = relationship('Thing', backref='votesreceived') 
    value = Column(Boolean) 

    def __init__(self, voter, thing, value): 
     if value is True: 
      thing.voteinfo.upvotes += 1 
     else: 
      thing.voteinfo.downvotes += 1 

當我嘗試運行此，我得到了「如果值爲True」的條款在此錯誤代碼：

AttributeError: 'InstrumentedList' object has no attribute 'upvotes' 

我已經嘗試給Voteinfo自己的唯一ID並添加uselist = False關係。我嘗試用VoteThing替換Voteinfo中的關係，但這也沒有幫助。我不知道InstrumentedList是什麼。到底是怎麼回事？

Answer 1

正如文檔中所述，此處：http://www.sqlalchemy.org/docs/orm/relationships.html#one-to-one，您必須添加uselist = False而不是關係，而是添加到backref。

thing = relationship('Thing', backref=backref('voteinfo', uselist=False))